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Flashcards in Integumentary System Deck (105)
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0
Q

Approximate how thick is the skin?

A

1-2 mm

1
Q

The integumentary system includes:

A
  1. Skin (cutaneous membrane)
      • epidermis
      • dermis
  2. Accessory structures (hair, oil & sweat glands, sensory receptors).
2
Q

Functions of integumentary system.

A
  1. Regulates body temperature
  2. Stores blood
  3. Protection from external environment
  4. Excretion and absorption
  5. Sensation
  6. Vitamin D synthesis
3
Q

Epidermis vs Dermis

A

Epidermis

    • more superficial, thinner
    • contains epithelial tissue
    • somewhat avascular

Dermis

    • deeper and thicker
    • contains connective tissue
    • vascularized
4
Q

Subcutaneous layer

A

AKA hypodermis

Not part of skin
Consists of areolar and adipose tissue

Functions: fat storage, blood vessel passage and location of pressure sensing nerve endings.

5
Q

The epidermis is primarily composed of what tissue type?

A

Stratified squamous epithelium

6
Q

4 principle cells of the epidermis

A

1 keratinocytes
2 melanocytes
3 Langerhans cell
4 Merkel cells

7
Q

Keratinocytes

A

90% of epidermal cells

Produce keratin and lamellae granules

8
Q

Keratin

A

Protein produced by keratinocytes

Protects skin and underlying tissue from heat, microbes and chemicals

Originate as tonofilaments which are converted by keratohyalin into keratin in the stratum granulosum.

9
Q

Lamellae granules.

A

Released by keratinocytes in stratum granulosum and stratum corneum

Produce water repellant sealant
Decreases entry of water and foreign materials (and water loss too).

10
Q

Melanocytes

A

In epidermis

Produce melanin

11
Q

Melanin

A

Pigment produced by melanocytes and transferred to keratinocytes

Absorb damaging UV light
Shield nucleus of keratinocytes

12
Q

Langerhans Cells

A

AKA Intraepidermal Macrophage cells

Epidermal dendritic cells
Arise from RBM and migrate to epidermis.

Participate in immune responses against invading microbes. Antigen presenting.

13
Q

Merkel Cells

A

AKA tactile epithelial cells

Least numerous epidermal cell
In deepest layer of epidermis.

Contact Merkel/tactile disc. Detect touch.

14
Q

Five layers of the epidermis

A
  1. Stratum basale/germinativum
  2. Stratum spinosum
  3. Stratum granulosum
  4. Stratum lucidum (palms and soles)
  5. Stratum corneum
15
Q

Stratum basale

A

AKA stratum germinativum

Deepest epidermal layer
SINGLE row of cuboidal or columnar keratinocytes

Also contain melanocytes, Merkel cells and stem cells (which produce keratinocytes)

If this layer is destroyed skin cannot regenerate

Cells attach to each other by desmosomes and to basement membrane by hemidesmosomes

16
Q

Stratum spinosum

A

8-10 cells layers held together by desmosomes
Second deepest layer or epidermis

Mostly keratinocytes but also Langerhans cells and melanocyte projections.

17
Q

Stratum granulosum.

A

Epidermis

3-5 layers of flat cells undergoing apoptosis

Transition layer between deeper active strata and superficial dead cells.

Keratinocytes release lamellae granules.
Contain keratohyalin which converts tonofilaments into keratin

18
Q

Stratum lucidum

A

Layer of epidermis only found in finger tips, palms and soles of feet.

4-6 layers of flat dead cells.

Add additional toughness

19
Q

Stratum corneum

A

25-30 layers of flat dead cells filled by keratin and surrounded by lipids

Most superficial layer of epidermis

Contain lamellar granules.

Protect against light, heat, chemicals and bacteria

20
Q

Callus

A

Abnormal thickening of the stratum corneum of the epidermis due to friction.

21
Q

Keratinization

A

Replacement of cell contents with keratin as cells move to skin surface

Takes 4-6 weeks.

Stem cells product keratinocytes.
Keratinocytes contain tonofilaments which are converted to keratin by keratohyalin in the stratum granulosum.

Epidermal growth factor (EGF) involved.

22
Q

Dermis is composed primarily of what tissue type?

A

Dense irregular connective tissue containing collagen and elastin fibres

23
Q

The Dermis contains:

A

Fibres (collagen and elastin)

Cells (fibroblasts, macrophages, fat cells)

Hair follicles, glands, nerves and blood vessels.

24
Q

Elasticity

A

Ability to return back to the original shape

25
Q

Extensibility

A

Ability to stretch

26
Q

Tensile strength

A

Ability to resist pulling or stretching.

27
Q

Two major regions of the dermis

A

Papillary and reticular

28
Q

Papillary region

A

Top 20% of dermis

Thin collagen and elastic fibres
Mostly fibroblasts

Has dermal papillae (epidermal ridges)

29
Q

Dermal papillae

A

AKA dermal ridges

Anchor papillary region of dermis to epidermis.
Increase surface area of papillary region
Contain capillaries that feed epidermis
Contain Meissner’s corpuscles (touch) and free nerve endings that sense heat/cold/pain/tickling/itch

30
Q

Reticular region

A

Deeper 80% of dermis

Attached to subcutaneous layer.

Consists of:

  • thick collagen fibres
  • fibroblasts
  • wandering cells
  • some adipose cells
  • blood vessels, nerves, sebaceous and sudiferous glands, ducts and hair follicles.
31
Q

Epidermal ridges

A

In the dermis. Not the epidermis. Doh!

Make fingerprints.
Also increases friction, and increases number of Meisnner corpuscles and hence tactile sensitivity.

32
Q

Skin colour is due to what pigments?

A

(All in dermis)

Melanin
Carotene
Hemoglobin

33
Q

Freckles vs moles

A

Freckles: excess melanin

Moles: excess melanocytes

34
Q

Albinism

A

Inability to produce tyrosinase and thus melanin.

35
Q

Vitiligo

A

Loss of melanocytes

36
Q

Jaundice

A

Buildup of bilirubin

37
Q

Cyanosis

A

Bluish tinge due to low oxygen

38
Q

Pallor

A

Paleness due to low blood level (shock, anemia)

39
Q

Development of accessory structures of skin

A

Develop from embryonic epidermis.

Cells sink inward to form hair, nails and glands.

40
Q

Hair consists of:

A
  1. Shaft (projects above skin)

2. Root (below skin surface)

41
Q

What are the three layers of hair (shaft and root)?

A

Medulla
Cortex
Cuticle

42
Q

Epithelial root sheath

A

AKA the hair follicle

External root sheath + Internal root sheath

Exists on root only.

43
Q

Downward continuation of epidermis onto hair root.

A

External root sheath

44
Q

Hair bulb

A

Base of each hair follicle
Nourishes growing follicle
Contains hair matrix

45
Q

Hair matrix

A

Germinal layer of cells contained in hair bulb.

Site of cell division.

Arises from stratum basale.

46
Q

Arrector pili

A

Smooth muscle in dermis
Contracts with cold or fear
Creates goose bumps

47
Q

Hair root plexus

A

Dendrites of neurons that detect hair movement and sense touch.

48
Q

Normal rate of hair loss

A

70-100 hairs/day

49
Q

Three stages of hair growth

A

Growth stage
Regression stage
Resting stage

50
Q

Growth stage of hair growth

A

2-6 years

Matrix cells active producing length

At any time 85% of hair in growth stage.

51
Q

Regression stage of hair growth

A

2-3 weeks

Matrix cells stop dividing, follicles atrophy and hair stops growing.

52
Q

Resting stage of hair growth

A

3 months.

Afterwards, new growth stage begins

53
Q

Lanugo

A

Fine, nonpigmented, downy hair covering fetus.

54
Q

Terminal hair

A

Replaces lanugo prior to birth

Course, pigmented hair on eyebrows, eyelashes, scalp.

55
Q

Velus hair

A

Short, fine, pale body hair. Replaces lanugo over body.

56
Q

What happens to hair at puberty?

A

In response to androgens, terminal hairs replace vellus hairs at axilla, private bits, etc.

In adults: males 95% terminal; females 35% terminal

57
Q

Hair colour: causes

A

Dark hair: true melanin
Blonde and red: melanin with iron and sulfur
Graying hair: decline in melanin production
White hair: lack of melanin and air bubbles in medullary shaft.

58
Q

Two types of melanin

A

Eumelanin: brown to black

Pheomelanin: yellow to red

59
Q

Alopecia

A

Partial or complete loss of hair

60
Q

Hirsutism

A

Excessive body hair linked to excess androgen.

61
Q

Three components of a nail

A
  1. Nail body
  2. Free edge
  3. Nail root.
62
Q

Decubitus ulcer

A

Pressure sore

Deficiency of blood flow causes tissue ulceration.

63
Q

Erythema

A

Redness of skin due to enlargement of capillaries in dermis.

Inflammation, infection, allergy, burn.

64
Q

Psoriasis

A

Chronic skin condition characterized by rapid cell division and movement of keratinocytes through epidermal area.

Also production off abnormal keratin.

65
Q

Striae

A

Stretch marks

Dermal blood vessels rupture when skin is overstretched and bonds between collagen fibres break. Results in silvery white streaks.

66
Q

Dandruff

A

Excessive amount of keratinized cells shed from scalp.

67
Q

Tension lines

A

AKA lines of cleavage.

Orientation of collagen fibres in reticular region. Indicate predominant direction of underlying collagen fibres.

68
Q

Age spots

A

AKA liver spots

Accumulation of melanin over time due to sun damage.

69
Q

Nail body

A

Visible portion of nail

70
Q

Lunula

A

Whitish “half moon” at proximal end of nail.

Capillaries not visible through thickened epithelium.

71
Q

Free edge

A

Part of nail that extends past digit

72
Q

Nail root

A

Part of nail buried in fold of skin

73
Q

Function of nails

A
  1. Protection
  2. Counter pressure
  3. Grasp and manipulate small objects
  4. Scratching and grooming.
74
Q

Hyponychium

A

Nail bed

Thickened stratum corneum.
Attaches nail to fingertips

75
Q

Eponychium

A

Cuticle

Narrow band of epidermis (stratum corneum) that extends from and adheres to lateral side of nail wall.

76
Q

Nail matrix

A

Proximal portion of epithelium deep to nail root whose cells divide mitotically

Transformation of superficial nail matrix cells into new nail cells –> how nails grow. (Average 1 mm/week)

77
Q

Glands of the skin

A

Exocrine glands in the dermis

78
Q

Four types of skin glands

A

1 sebaceous
2. Sudiferous
3 ceruminous
4. Mammary

79
Q

Sebaceous glands

A

Oil glands. Produce sebum.
Less active before puberty.

Opens into neck of hair follicle.

Absent in palms and soles.

80
Q

Sebum

A

Released by sebaceous glands.

Cholesterol, proteins, fats and salts.

Moistens, waterproofs, protects agains bacteria and fungi.

81
Q

Sudiferous glands: two types

A

Sweat glands.

Eccrine
Apocrine

82
Q

Eccrine glands

A

Ducts terminate at sweat pores on skin surface.

Develop and function soon after birth.

Functions:

  1. Thermoregulation
  2. Emotional sweating
  3. Waste elimination (urea, ammonia, salt)
83
Q

Apocrine glands

A

Sudiferous glands that start working at puberty.
Axilla, groin, areolae, etc

Sweat is cloudy and smelly.

84
Q

Ceruminous glands

A

Makers of ear wax (cerumen) = combination of ceruminous and sebaceous secretions.

85
Q

Thermoregulation

A

Homeostatic regulation of body temperature

86
Q

Stages of epidermal wound healing

A

Abrasion, minor burn

Basal cells migrate across wound
Contact inhibition
Epidermal growth factor stimulates basal cell division

87
Q

Phases of deep wound healing

A
  1. Inflammatory
  2. Migratory
  3. Proliferative
  4. Maturation.
88
Q

Inflammatory phase

A

Clot unites wound edges and WBCs arrive from dilated and more permeable blood vessels.

89
Q

Migratory phase

A

Regrowth of epithelial cells begins and start of scar tissue formation by fibroblasts.

Wound fills with Granulation tissue.

90
Q

Proliferative phase

A

Completion of tissue formation.

Random laying down of collagen fibres.

Continued revascularization

91
Q

Maturation phase of healing

A

Scab falls off

Collagen becomes more organized.
Fibroblasts disappear.

92
Q

Fibrosis

A

Scar tissue formation

Collagen fibres more densely arranged.
Decreased elasticity
Fewer blood vessels

93
Q

Epidermis derives from which germ layer.

A

Ectodermal

Leads to hair, nails, skin.

94
Q

Dermis arises from which germ layer.

A

Mesenchymal.

Blood tissue and connective tissue too.

95
Q

Vernix caseosa

A

“Cheese varnish”

Slippery oil coating on neonates. Protects from amniotic fluid.

96
Q

UVA rays

A

Penetrate furthest into skin.
Absorbed by melanocytes.
Depress immune system.

97
Q

UVB rays

A

Don’t penetrate as deeply as UVA rays.

Cause sunburns and most tissue damages.

98
Q

Basal cell carcinoma

A

78% of all skin cancers

Tumours in stratum basale
Rarely metastasize.

99
Q

Squamous cell carcinoma

A

20% of all skin cancers.

Tumours in stratum spinosum

May metastasize.

100
Q

Malignant melanoma

A

Affects melanocytes.

101
Q

Major burn

A

3rd degree burn over 10% of body, or on face, hands, feet or perineum

2nd degree burn over 25% of body.

102
Q

First degree burn

A

Only epidermis

103
Q

Second degree burn

A

Destroys entire epidermis and part of dermis

Characterized by fluid filled blisters

Heals without grafting in 3-4 weeks

104
Q

Third degree

A

Destroys epidermis, dermis and epidermal derivatives and subQ layer

Most skin functions, sensation lost.